This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our goal is to perform studies on early intrauterine pregnancy (IUP) in rhesus macaques. During pregnancy the vessels of the endometrium are extensively modified to provide blood flow to the growing conceptus. Contrast-enhanced ultrasound (CEU) is a new technique capable of high-resolution imaging of the microvasculature within organs. The method relies on the detection of gas-filled microbubbles that are injected intravenously while imaging by ultrasound. Our hypothesis is that CEU imaging will permit earlier visualization of embryo implantation and for the first time a detailed evaluation of the growing endometrial vessels at the fetal-maternal interface. Our Specific Aim is to develop microbubble CEU for visualization of early pregnancy and assessment of intrauterine vascular parameters during embryo implantation in rhesus macaques. This aim is underway and we have imaged the endometrium during early pregnancy in 5 rhesus macaques. An extension of our hypothesis is that microbubble CEU may be a useful tool in the study and early diagnosis of pregnancy disorders including ectopic pregnancy (EP). EP is a serious condition where a developing conceptus attaches and implants outside the uterus, most frequently within the fallopian tube. Early diagnosis is essential for successful treatment of EP, and we plan to explore a new model for experimentally-induced EP in rhesus macaques.